The present invention relates to a technique effective in application for the wirings that transmit to the following stage amplifier the output of a mixer of the direct down-conversion system that synthesizes a reception signal and an oscillation signal of a predetermined frequency to produce a frequency-converted signal, in a semiconductor integrated circuit used in a radio communication system; especially, it relates to a technique effective in use for a semiconductor integrated circuit having a function that modulates/demodulates a transmission/reception signal, which is used in a radio communication system capable of transmitting/receiving signals of plural bands.
A radio communication system such as a mobile telephone generally uses a VCO (Voltage Controlled Oscillator) that generates an oscillation signal of a predetermined frequency that is synthesized with a reception signal or a transmission signal. Some of the conventionally proposed mobile telephones take on the so-called dual band system that can handle the signals of two frequency bands such as the GSM (Global System For Mobile Communication) of 880 to 915 MHz band and the DCS (Digital Cellular System) of 1710 to 1785 MHz band.
In recent years, there appears a demand for the triple band system that can handle the signal of the PCS (Personal Communication System) of 1850 to 1915 MHz band, in addition to the GSM and DCS. It is also conceivable that there will increase a demand for a mobile telephone capable of handling more bands.